373 research outputs found
A simple model of space radiation damage in GaAs solar cells
A simple model is derived for the radiation damage of shallow junction gallium arsenide (GaAs) solar cells. Reasonable agreement is found between the model and specific experimental studies of radiation effects with electron and proton beams. In particular, the extreme sensitivity of the cell to protons stopping near the cell junction is predicted by the model. The equivalent fluence concept is of questionable validity for monoenergetic proton beams. Angular factors are quite important in establishing the cell sensitivity to incident particle types and energies. A fluence of isotropic incidence 1 MeV electrons (assuming infinite backing) is equivalent to four times the fluence of normal incidence 1 MeV electrons. Spectral factors common to the space radiations are considered, and cover glass thickness required to minimize the initial damage for a typical cell configuration is calculated. Rough equivalence between the geosynchronous environment and an equivalent 1 MeV electron fluence (normal incidence) is established
Computer simulation of radiation damage in gallium arsenide
A version of the binary-collision simulation code MARLOWE was used to study the spatial characteristics of radiation damage in proton and electron irradiated gallium arsenide. Comparisons made with the experimental results proved to be encouraging
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Scavenging of black carbon by ice crystals over the northern Pacific
Airborne measurements over the northern Pacific are
evaluated to characterize properties of black carbon (BC) in
cirrus crystal residuals and background aerosols in the upper
troposphere. Although the mass and number concentrations
of BC were 7ā25 times lower in crystal residuals than in
particles outside of cloud, twice as many of the residuals
(31%) contained BC compared to 17% of the particles in
cloud-free air. In addition the average mass equivalent
diameter (MED) of BC was 10% larger in crystal residuals
than in particles outside of cloud. These differences in
crystal residuals compared to the background aerosols
suggest that inertial scavenging is a significant mechanism
for removing BC compared to removal by nucleation. The
scavenging efficiency, calculated as the BC mass in
condensed cloud water, ranged from 7ā44 ng of carbon per
gram of water, consistent with previous studies in marine
stratus clouds
DNA polymerases Ī¶ and Rev1 mediate error-prone bypass of non-B DNA structures
DNA polymerase Ī¶ (Pol Ī¶) and Rev1 are key players in translesion DNA synthesis. The error-prone Pol Ī¶ can also participate in replication of undamaged DNA when the normal replisome is impaired. Here we define the nature of the replication disturbances that trigger the recruitment of error-prone polymerases in the absence of DNA damage and describe the specific roles of Rev1 and Pol Ī¶ in handling these disturbances. We show that Pol Ī¶/Rev1-dependent mutations occur at sites of replication stalling at short repeated sequences capable of forming hairpin structures. The Rev1 deoxycytidyl transferase can take over the stalled replicative polymerase and incorporate an additional āCā at the hairpin base. Full hairpin bypass often involves template-switching DNA synthesis, subsequent realignment generating multiply mismatched primer termini and extension of these termini by Pol Ī¶. The postreplicative pathway dependent on polyubiquitylation of proliferating cell nuclear antigen provides a backup mechanism for accurate bypass of these sequences that is primarily used when the Pol Ī¶/Rev1-dependent pathway is inactive. The results emphasize the pivotal role of noncanonical DNA structures in mutagenesis and reveal the long-sought-after mechanism of complex mutations that represent a unique signature of Pol Ī¶
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Observations of ice nuclei and heterogeneous freezing in a Western Pacific extratropical storm
In situ airborne sampling of refractory black carbon (rBC) particles and Ice Nuclei (IN) was conducted in and near an extratropical cyclonic storm in the western Pacific Ocean during the Pacific Dust Experiment, PACDEX, in the spring of 2007. Airmass origins were from Eastern Asia. Clouds associated primarily with the warm sector of the storm were sampled at various locations and altitudes. Cloud hydrometeors were evaporated by a counterflow virtual impactor (CVI) and the residuals were sampled by a single particle soot photometer (SP2) instrument, a continuous flow diffusion chamber ice nucleus detector (CFDC) and collected for electron microscope analysis. In clouds containing large ice particles, multiple residual particles were observed downstream of the CVI for each ice particle sampled on average. The fraction of rBC compared to total particles in the residual particles increased with decreasing condensed water content, while the fraction of IN compared to total particles did not, suggesting that the scavenging process for rBC is different than for IN. In the warm sector storm midlevels at temperatures where heterogeneous freezing is expected to be significant (here ā24 to ā29 Ā°C), IN concentrations from ice particle residuals generally agreed with simultaneous measurements of total ice concentrations or were higher in regions where aggregates of crystals were found, suggesting heterogeneous freezing as the dominant ice formation process in the mid levels of these warm sector clouds. Lower in the storm, at warmer temperatures, ice concentrations were affected by aggregation and were somewhat less than measured IN concentrations at colder temperatures. The results are consistent with ice particles forming at storm mid-levels by heterogeneous freezing on IN, followed by aggregation and sedimentation to lower altitudes. Compositional analysis of the aerosol and back trajectories of the air in the warm sector suggested a possible biomass burning source for much of the aerosol. Comparison of the particles from the CFDC with the other aerosol in the residuals of ice particles suggested that the largest portion of IN had similar inferred origins (from biomass burning with minor amounts of rBC) as the other aerosol, but contained slightly elevated amounts of calcium and less influence from sea salt
The Future of American Sentencing: A National Roundtable on Blakely
In the wake of the dramatic Supreme Court decision in Blakely v. Washington, Stanford Law School convened an assembly of the most eminent academic and professional sentencing experts in the country to jointly assess the meaning of the decision and its implications for federal and state sentencing reform. The event took place on October 8 and 9, just a few months after Blakely came down and the very week that the Supreme Court heard the arguments in United States v. Booker and United States v. Fanfan, the cases that will test Blakely\u27s application to the Federal Sentencing Guidelines. Thus the Roundtable offered these experts an intellectual breathing space at a crucial point in American criminal law.
The event was built around six sessions, with shifting panels of participants doing brief presentations on the subject of the session, and with others then joining in the discussion. We are pleased that FSR is able to publish this version of the proceedings of the event-a condensed and edited transcript of the sessions
'You can take a horse to water but you can't make it drink': Exploring children's engagement and resistance in family therapy
The final publication is available at Springer via http://dx.doi.org/10.1007/s10591-012-9220-8Childrenās engagement and disengagement, adherence and non-adherence, compliance and non-compliance in healthcare have important implications for services. In family therapy mere attendance to the appointments is no guarantee of engaging in the treatment process and as children are not the main initiators of attendance engaging them through the process can be a complex activity for professionals. Through a conversation analysis of naturally occurring family therapy sessions we explore the main discursive strategies that children employ in this context to passively and actively disengage from the therapeutic process and investigate how the therapists manage and attend to this. We note that children competently remove themselves from therapy through passive resistance, active disengagement, and by expressing their autonomy. Analysis reveals that siblings of the constructed āproblemā child are given greater liberty in involvement. We conclude by demonstrating how therapists manage the delicate endeavour of including all family members in the process and how engagement and re-engagement are essential for meeting goals and discuss broader implications for healthcare and other settings where children may disengage
Microphysical characteristics of frozen droplet aggregates from deep convective clouds
During the 2012 Deep Convective Clouds and Chemistry
(DC3) experiment the National Science Foundation/National Center for
Atmospheric Research Gulfstream V (GV) aircraft sampled the upper anvils of
two storms that developed in eastern Colorado on 6Ā JuneĀ 2012. A cloud
particle imager (CPI) mounted on the GV aircraft recorded images of ice
crystals at altitudes of 12.0 to 12.4 km and temperatures (T) from ā61 to ā55 āC.
A total of 22 393 CPI crystal images were analyzed, all with maximum
dimension (Dmaxā”)<433 Āµm and with an average Dmaxā” of
80.7Ā±45.4 Āµm. The occurrence of well-defined pristine crystals
(e.g., columns and plates) was less than 0.04 % by number. Single frozen
droplets and frozen droplet aggregates (FDAs) were the dominant habits with
fractions of 73.0 % (by number) and 46.3 % (by projected area),
respectively. The relative frequency of occurrence of single frozen droplets
and FDAs depended on temperature and position within the anvil cloud.
A new algorithm that uses the circle Hough transform technique was developed
to automatically identify the number, size, and relative position of element
frozen droplets within FDAs. Of the FDAs, 42.0 % had two element frozen
droplets with an average of 4.7Ā±5.0 element frozen droplets. The
frequency of occurrence gradually decreased with the number of element frozen
droplets. Based on the number, size, and relative position of the element
frozen droplets within the FDAs, possible three-dimensional (3-D)
realizations of FDAs were generated and characterized by two different shape
parameters, the aggregation index (AI) and the fractal dimension (Df),
that describe 3-D shapes and link to scattering properties with an
assumption of spherical shape of element frozen droplets. The AI of FDAs
decreased with an increase in the number of element frozen droplets, with
larger FDAs with more element frozen droplets having more compact shapes.
The Df of FDAs was about 1.20ā1.43 smaller than that of black carbon
(BC) aggregates (1.53ā1.85) determined in previous studies. Such a smaller
Df of FDAs indicates that FDAs have more linear chain-like branched
shapes than the compact shapes of BC aggregates. Determined morphological
characteristics of FDAs along with the proposed reconstructed 3-D
representations of FDAs in this study have important implications for
improving the calculations of the microphysical (e.g., fall velocity) and radiative
(e.g., asymmetry parameter) properties of ice crystals in upper anvil
clouds.</p
Relationships between adverse childhood experiences and adult mental well-being: results from an English national household survey.
BACKGROUND: Individuals' childhood experiences can strongly influence their future health and well-being. Adverse childhood experiences (ACEs) such as abuse and dysfunctional home environments show strong cumulative relationships with physical and mental illness yet less is known about their effects on mental well-being in the general population. METHODS: A nationally representative household survey of English adults (nā=ā3,885) measuring current mental well-being (Short Edinburgh-Warwick Mental Well-being Scale SWEMWBS) and life satisfaction and retrospective exposure to nine ACEs. RESULTS: Almost half of participants (46.4Ā %) had suffered at least one ACE and 8.3Ā % had suffered four or more. Adjusted odds ratios (AORs) for low life satisfaction and low mental well-being increased with the number of ACEs. AORs for low ratings of all individual SWEMWBS components also increased with ACE count, particularly never or rarely feeling close to others. Of individual ACEs, growing up in a household affected by mental illness and suffering sexual abuse had the most relationships with markers of mental well-being. CONCLUSIONS: Childhood adversity has a strong cumulative relationship with adult mental well-being. Comprehensive mental health strategies should incorporate interventions to prevent ACEs and moderate their impacts from the very earliest stages of life
Negative attitudes related to violence against women: gender and ethnic differences among youth living in Serbia
OBJECTIVES: This study aimed to identify to what extent negative attitudes towards intimate partner violence against women are present among young women and men living in Serbia, in Roma and non-Roma settlements. METHODS: We used the data from the 2010 Multiple Indicator Cluster Survey conducted in Serbia, for the respondents who were 15-24Ā years old. Regression analyses were used to examine the association between judgmental attitudes, socio-demographic factors and life satisfaction. RESULTS: In Roma settlements, 34.8% of men and 23.6% of women believed that under certain circumstances men are justified to be violent towards wives, while among non-Roma it was 5.6 and 4.0%, respectively. These negative attitudes were significantly associated with lower educational level, lower socio-economic status and being married. In multivariate model, in both Roma and non-Roma population women who were not married were less judgmental, while the richest Roma men were least judgmental (OR 0.40, 95% CI 0.18-0.87). CONCLUSIONS: Violence prevention activities have to be focused on promoting gender equality among youth in vulnerable population groups such as Roma, especially through social support, strengthening their education and employment
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